They will, I give it a year, or two tops of tournaments where the Tau or Guard player with 60-70% of his army, looses to the CSM player with 1 model left before they go back entirely, or at least change their missions to VPs again.
I don't see 5th as sticking around for all that long, an interesting diversion into a different branch of dynamics, but it's alienating some of the older players and making a serious split between the younger and older generations, a 40k lite and a 40k real.
Just like 4th Edition for DnD, being a dumbed down boardgame system. It won't stick around for long, I just hope it's gone soon enough that I can get back into it.